AccuWeather.com

By John Marsh, AccuWeather.com Staff Writer

Feb 8, 2012; 12:08 PM ET

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Photo from Alaska Volcano Observatory.

Mount Cleveland, a volcano in Alaska, has been exhibiting "eruptive activity" according to the Alaska Volcano Observatory (AVO). If it erupts, the volcano could spew ash into the air, which can potentially threaten trans-Pacific flight paths.

Trans-Pacific flights could head directly over the area of the potential explosion. Depending on the altitude of the ash cloud produced by the explosion, travel may or may not be impacted.

"It really depends on the height of the ash cloud from the eruption, as well as when it erupts," said AccuWeather.com Senior Meteorologist Michael Pigott. "If the cloud were to stay around 20,000 feet and hit the air on Tuesday, things wouldn't be too bad. But that would change as winds begin to pick up significantly on Wednesday."

"The volcano at Mount Cleveland exploded twice on Christmas Day and once on Dec. 29. If an explosion were to happen soon and be similar to those explosions, the ash cloud will probably end up in the 15,000- to 20,000-foot range," said Alaska Volcano Observatory Research Geologist Matt Haney. "Essentially, this explosion would probably not have much of an impact on international travel as it will most likely not exceed 30,000 feet, where most flights in the area would be traveling. That's what we're thinking right now."

Haney continued, "Cleveland is one of the most active volcanoes in the arc and it erupts once or twice almost every year. In the last 4 or 5 years, most of the explosions have been 'minor.' However, back in 2001, it was more powerful. The ash cloud went upwards of 30,000 to 40,000 feet."

"If you were talking about 30,000 to 40,000 feet, things would be different. Potentially, the ash could move quite a far distance. If the ash cloud goes higher, it could hit the jet stream and head out over Canada. Wind currents are very strong through Wednesday evening, but will ease off overnight. If the explosion happened then and reached that altitude, it probably wouldn't be as bad of a situation," said Pigott.

Photo from the Alaska Volcano Observatory

On Jan. 30, a 130-foot (40-meter) lava dome was first observed from satellite data after a month of little to no change. The diameter of the opening of the volcano is approximately 650 feet (200 meters). Since this lava dome formed, no observations of ash emissions or explosive activity have been reported.

"Think of a lava dome as a sort-of 'plug' that forms at the top of the conduit," Haney said. "Lava domes usually form in strata volcanoes. If the dome were to plug up the conduit completely, pressure could build up and lead to a new explosion. Generally, a dome is indicative of explosive activity. What we're trying to determine now is if this dome will be destroyed or if it's the final cap for this round of activity."

The most recent report from the AVO shows no evidence of ash emissions or elevated surface temperatures in partly cloudy satellite images over the past 24 hours. Additionally, there are no indications of any explosive ash-producing activity from the volcano. According to the AVO, eruptive activity at the volcano has slowed or even paused.

Still, the AVO warns that "intermittent, sudden explosions of blocks and ash" can occur at any time and ash clouds of up to 20,000 feet above sea level may form, and they have issued a volcano "watch," color code "orange."

"Since Mount Cleveland is on a small volcanic island in the Aleutian Island chain, we don't have real-time monitoring," added Haney. "We monitor with satellites, ground-based seismic monitors and infra-sound detectors. Nearby islands, however, do have real-time monitoring, and if a major explosion came from Mount Cleveland, we would know about it."

Information in this story was provided by the AVO.